CHT/EGT selector switch?

[Birdseyeview]

I've got the Rotax 912 supplied CHT senders already on the engine and haven't purchased any EGT probes yet. I've also got a Westach quad gauge which only monitors one CHT and one EGT at a time. Any recommendations on which cylinder I should monitor, or should I get a selector switch and monitor them all? Spruce has these switches and I could get one for all the CHT senders and another one for all the EGT senders. Also, what location in an exhaust pipe is best on the 912 for mounting an EGT probe?

[avidflyer]

I have one of those 4 position switches from ACS that you mention. You can actually use the same switch for CHT and EGT. As the switch comes, it has wires on only one side, but there are connections on the opposite side of the switch that you can connect to. That is what I did with my Avid Flyer with the 4 cylinder Jabiru engine in it. In # 1 position, I'm reading #1 cylinder EGT and CHT, in position #2, #2 cylinder EGT and CHT, ect, ect. I usually just leave it on #3 cylinder as that one runs the hottest. Once in a while I will switch through and look at what the others are doing. JImChuk


PS I just went to Westach's site, and looked at that switch there. Looks like you can get the switch wired for the other 4 termanials from them (model 254-4FD) or just wire the cheaper model 254-4F yourself westach.com/products/ACCESSORIES/SWITCHES/SWITCHES%20FOR%20THERMOCOUPLES/index.php

[Birdseyeview]

Thanks for the info avid flyer. Just curious, do you have your selector switch mounted on the instrument panel near your associated temp gauge or somewhere else a little more out of the way since you don't use it often?

[avidflyer]

If I can post it, here is a pic of my panel. I use an MGL-E1 engine monitor for CHT and EGT and the 4 way switch is right below it. After much back and forth, I think I figured out how to reduce the size of the photos. The panel is not finished of course in this picture, but it does show the switch and such. JImChuk

[Birdseyeview]

I'm assuming that your MGL engine monitor only shows one cylinder at a time, and that's where the need for the rotary switch arrises. Now that you've had the ability to monitor all the cylinders for a while would you do it differently if you were doing it again? For instance and for simplicities sake, would you only monitor the temps on one cylinder and ignore the rest and eliminate the switch and a few temp probes? What's your take on the reliability of the switch? I saw someones comments in the Spruce catalog review that he had to replace his switch every 3 years. In your situation and set up do you worry more about CHT or EGT? I know this isn't exactly a fair comparison to my Rotax 912 but I'm trying to get at the underlying logic for what is important to monitor and what my options to display it are, while staying within the confines of my existing quad gauge. I also have an underlying goal of keeping my panel and wiring as simple as possible but a rotary switch would certainly be included if its function fulfills a key need.

[avidflyer]

I think it's nice to be able to see all 4 temps when you want to. I'm rebuilding a Kitfox that will have a 912 in it, and will maybe go the same route. I've never had trouble with the switch, actually I used to have 2 of them, one for CHT, and one for EGT. When I rebuilt the plane and panel, I learned I could use just one. The Jabiru may be a bit more finicky then the 912, so maybe monitoring all 4 cylinders is better with it than the 912. My monitor could see 2 EGTs and 2 CHTs at once, but I only use one side. Looks like all you would need is 4 EGT probes plus the switch, and this should work fine on your quad gauge. I would probably go with it. JImChuk